I can’t find an off the shelf solution in the UK as an alternative to a bubble air lock. I’m trying to avoid suck back when bottling and cold crashing when using the Grainfather Conical Fermenter.
A Plaato Valve also does what you’re describing, although they might be difficult to get hold of now that Plaato don’t seem to support their products. It’s a simple one way valve that fits inline with the blow-off tube from the fermenter
Because the volume of the liquid is much less (filled correctly) than the volume of the space it would need to travel to be sucked back.
Don't compare these to an S shaped bubbler. I have these on all my stainless tanks. They don't suck back, and if you are concerned simply lift the cap. Consider also thicker water